This invention relates to a highly conductive styrenic resin composition excellent in mechanical properties, especially impact resistance.
Because of their excellent moldability, processability, mechanical strength, and electrical insulating properties, styrene resins such as styrene homopolymers, styrene-based copolymers, rubber-reinforced high-impact polystyrene, and ABS resins (polymers prepared by graft-polymerizing butadiene elastomer or a derivative thereof with both styrene and acrylonitrile monomer) have been used as molding materials in a variety of application fields. On the other hand, for lack of conductivity, they have various problems such as static electricity charging and a trouble caused by electromagnetic waves.
Accordingly, attempts have been made to impart to styrene resin, as in the case of other resins, a high conductivity so as to provide a sufficient effect of shielding electromagnetic waves.
It has been well-known that a resin can be given a high conductivity by filling it with one or more highly conductive fillers such as carbon black, carbon fiber, metal-coated glass fiber, metallic fiber, metal flakes, or metal powder. Among these highly conductive fillers, metallic fillers have widely been used because of their good balance between the cost and the conductivity-imparting abilities.
Imparting a high conductivity to styrene resin has also been performed by filling the resin with a metallic filler. Although a high conductivity can be obtained by filling a conventional styrene resin with a metallic filler, there is a drawback that the mechanical strength, especially impact resistance of the produced highly conductive resin is lowered remarkably as compared with that of the base styrene resin, and therefore improvement of this drawback has been desired.